The present invention relates to a connecting device for an electrical installation system for controlling consuming devices and/or for redirecting status signals over a data line from an external bus line using serial digital data transfer. The connecting device passes control and/or status information from the external bus line through a base module, having a bus coupling unit, to function-specific expansion modules with digital and/or analog inputs and/or outputs for the respective consuming devices. The expansion modules are interconnectable with the basic module in an internally communicating manner.
Systems which use a bus line within a building for transferring data and signals for controlling consuming devices are known. For this purpose, so-called "intelligent" consuming devices are used into each of which a dedicated bus coupling unit is integrated. If a signal is now supplied to the bus by means of a switch, which is also connected in the bus line over a dedicated bus coupling, each consuming device selects the signal specific for it by means of its own bus coupling unit, that is, each consumer-side bus coupling unit is addressed in a defined manner with the signal and, with that, the consuming device is operated. It is a disadvantage here that, as a result of the dedicated bus coupling unit, the consuming device becomes more expensive than normal consuming devices.
The DE 42 00 818 A1 and also the Wieland publication, WIB Wieland Installations Bus, Imprint 0054 . 1Mu 9.92, disclose a distributor, which is connected in a bus line and has dedicated bus coupling units which are followed by appropriate switching elements. In this system, the bus couplers analyze the signals supplied by the building bus and switch the switching device following them, such as a relay, appropriately. Consequently, the bus line is no longer directly connected to the consuming device so that the latter does not have to be equipped with the expensive bus coupling unit. Instead, the consuming device is operated directly with the load line. However, it is a disadvantage of this system that, in view of the many possible functions which can be or must be carried out, the distributor must be dimensioned much too large to include all these functions. Furthermore, a complete new distributor must be used when retrofitting which is also very cost intensive.
Moreover, the DE 40 19 465 A1 publication discloses a connecting device which consists of a basic module having a bus coupling unit and to which function-specific expansion modules, which are designed for specific user functions, are connected. The construction of this device is such that, starting out from the basic module, in each case a dedicated communication line is applied to each expansion module. By means of this line, the respective modules communicate with one another, the data being identified and redirected to the specific module by means of a microprocessor integrated in the basic module. However, the function of the individual modules themselves is disadvantageously specified by the pre-programming of the microprocessor and cannot be varied. Their use is therefore limited to these predetermined functions. Expansion modules merely represent implementing subunits, since they are merely implementing components which are addressed specifically by the sole microprocessor, the capacity of which is limited.
Furthermore, since the microprocessor, with its specified connection possibilities, is connected in each case with one expansion module, a maximum number of modules which can be connected is limited. It is furthermore a disadvantage that a separate communication line must be provided for each expansion module; this creates difficulties with respect to keeping the dimensions as small as possible. Moreover, because of the permanently installed communication lines, an expansion after permanent installation--if possible at all, in view of the small maximum number of modules specified by the possible connections of the processor--is not possible or possible only with difficulty, since either a new line will have to be laid directly to the processor or, if unused lines are passed through the module, these lines will first have to be extended or at least connected in the form described in the DE 40 19 465 A1, neither of which is done easily.